Should I replace the crank and big end bearings because the oil pan is off anyway ?

[relaxedcruiser]

Hi guys
I have a slight and barely dripping oil leak from the sump gasket since ages - just not bad enough to do it right away but it annoys me every time I look at it. Engine has unknown milage - the PO rebuild it with new pistons but left the original bearings in there, "they were just fine" He said when I bought the 60 with the 12HT almost 10 years ago. I was not impressed by that.
Oil pressure is ok as per FSM. I have all the (top quality japanese) bearings at hand - should I replace them as a preventive service while I'm there ? Or follow the "never change a running team" rule ? Of course I'd check the clearances of the new bearings with plastigauge.
I'm probably too curious to leave them alone ... What are your thoughts ?

 

[Eurasiaoverland]

AFAIK the 12H-T has an issue with rings wearing the non Alfin original pistons, but I don't think it has the BEB issues of the 1HD.

I personally would rather not cycle the tension in the conrod bolts for no reason, because they are going to be pretty much impossible to replace in situ (assuming the bolts are in the rods, not the caps).

 

[relaxedcruiser]

Luckely I have the Alfin pistons already and I believe there are no worries in terms of taking the caps off multiple times.
I might anyway not have the time to do things which are not absolutely important before the new year. Need to replace the clutch first.

 

[TheBussman]

As long as it's not an engine that's not known for bearing problems there is nothing wrong with running the old bearings. I've had a few 400,000 mile engine apart because piston, ring or head wear and they had bearings that you could have convinced me were new. The rods that have studs and nuts can be a little tricky, sometimes the stud will rotate while you angle torque the nut and you may not notice if you don't also mark the stud. don't want to stretch it out, studs can be replaced in the truck but it is a pain. If you have any thing that makes you question it I would send you oil to a lab for analysis.